"Physical discs are so 20th century," I wrote back in 2006, when I began experimenting with using, in my high-end rig, a computer as a legitimate source of music. These days I rarely pop a disc into my Ayre Acoustics C-5xe^MP disc player, unless it's an SACD I want to hear, or a CD I haven't yet ripped into my library. But many audiophiles, even if attracted to the idea of using a file-based system as a primary music source, do not want a computer in their listening rooms. Nor do they want to be bothered by the fact that a computer demands too intimate a relationship with its user.

No one can say precisely how or when the ancient 300B triode tube made its cross-kingdom leap to the modern world of consumer audio, but we've got the where pretty much nailed down: It all began in Asia, where the best of the West is sometimes held in reverence rather than left to drown in consumerism's wake. Asia is the final resting place for the great Western Electric cinema systems of the 1940s—and that's where the 300B earned its un-American second act. By the mid-1990s, the tube had captured the hearts of hobbyists who, consciously or not, sensed that the audio refineries of the day had lost the plot, not to mention the body.